KR20130139239A - Inductive power transfer control - Google Patents

Abstract

An IPT control method is disclosed for controlling the output of an inductive power transfer (IPT) pickup. The present invention involves selectively rectifying an AC current input for supplying a load or selectively shunting the first and second diodes of a diode bridge to recycle the AC current to a resonant circuit coupled to the input of the controller. . By controlling the ratio of each positive-negative cycle of the rectified / recycled AC input, the output is regulated. Also disclosed is an IPT controller adapted to perform the method, an IPT pickup incorporating the IPT controller, and an IPT system incorporating at least one such IPT pickup.

Description

Inductive power transfer control {INDUCTIVE POWER TRANSFER CONTROL}

The present invention is in the field of inductive power transfer. More specifically, the present invention relates to a method and circuit for controlling the inductive transmission of power to a decoupling pick-up that minimizes transient disturbance to track current.

In inductive power transfer (IPT) systems, the power is a primary conductive path or track supplied by an alternating current power source (track and power source that together form the primary side of the IPT system), and the track (secondary side of the system). And inductively coupled between one or more pickups that are inductively coupled.

The pickup comprises a tuning or resonant circuit consisting of at least a pick-up coil and a tuning capacitor. Two common pick-up topologies are a series tuned pickup in which a tuning capacitor is provided in series with the pickup coil, and a parallel tuned pickup in which the tuning capacitor is provided in parallel with the pickup coil. The tuning circuit is typically electrically coupled to a control circuit (typically including a rectifier and a converter or regulator) to obtain the desired output for supplying the load.

An alternative pick-up topology is known as a series parallel parallel tuned LCL (inductor-capacitor-inductor) pickup, as shown by way of example in FIG. 1.

The serial parallel tuned LCL pickup topology (hereinafter referred to as LCL pickup) is controlled by a slow switching (i.e., a switching frequency much smaller than the frequency of the IPT track) decoupling control method similar to the slow switching parallel-tuned pickup. A problem with slow switching topologies is the transient inrush power that is drawn by the pickup during normal power regulation. In many pickup systems, whenever the pickup is switched on, transient power inrush transiently reduces the track current. This disturbance, when large, will limit power flow to all other pickups coupled to the track. A control circuit topology that minimizes this track current transient disturbance using a parallel LC tuned pickup controller is described in Boys, J.T .; Chen, C. I .; Covic, G. A .; "Controlling inrush currents in inductively coupled power systems," The 7th International Power Engineering Conference, 2005, Vol. 2, pp. 1046-1051, Nov. 29 2005-Dec. 2 is described by 2005. However, this simple approach cannot be used in LCL topologies using existing design approaches, since it requires a large DC inductor for continuous current conduction in switch mode circuits.

It is therefore an object of the present invention to provide a circuit and / or method that overcomes or ameliorates one or more disadvantages of the prior art, or alternatively to provide a useful choice for the public.

Other objects of the present invention will become apparent from the following description.

Thus, in one aspect, the invention can be said to be broadly configured as a control method for an inductive power transfer (IPT) pickup including an AC input from a resonant circuit, the AC input rectifying AC current from the AC input and DC Electrically coupled to a diode bridge adapted to supply current to the DC output, the method further comprising: causing the AC current to be recycled to the resonant circuit during the positive period of the AC current; Selectively shunting a first diode of the diode bridge; And selectively shunting a second diode of the diode bridge to cause the AC current to be recycled to the resonant circuit during a negative period of the AC current; The shunt of the first and second diodes is synchronized with the AC current, whereby a predetermined ratio of the positive and negative periods of the AC current is rectified to supply the DC current to the DC output, and the AC The remaining ratio of the positive and negative periods of current is recycled to the resonant circuit.

Advantageously, said predetermined ratio occurs at the initiation of each of said positive and negative periods of said AC current, and said first or second diodes respectively after said zero-crossing of AC current. Current is conducted and the remaining ratio of the positive or negative period is recycled by shunting each of the first or second diodes at an appropriate time. This mode of operation in which the diode is first conducted is referred to as mode I in this document.

Alternatively, the predetermined ratio occurs towards the end of each of the positive and negative periods of the AC current, and the first or second diodes respectively each of the AC current to initially recycle the AC current. Shunt according to the sign transform point of, wherein each of the first or second diodes is not shunted to conduct the AC current at the predetermined ratio of the positive or negative period. This mode of operation in which the diode is first divided is referred to as mode II in this document.

Advantageously, said predetermined ratio of positive and negative periods is proportional to a desired DC output, and said method further comprises sensing said DC output and adjusting said predetermined ratio appropriately to obtain said desired DC output. It further includes.

Advantageously, the method further comprises gradually increasing said predetermined rate to a desired rate upon switching on of said pickup.

Advantageously, the method further comprises gradually reducing said predetermined ratio to zero upon switching off of said pickup.

Preferably, the shunt is selectively controlled by selectively closing the first and second switches provided in parallel with each of the first and second diodes.

Advantageously, said first and second switching are opened when each of said first or second diodes is conducting.

Preferably, the resonant circuit comprises a series parallel tuning LCL (inductor-capacitor-inductor) pickup circuit.

According to a second aspect, the invention can be said to be broadly constructed with an IPT pickup controller adapted to carry out the method according to the first aspect of the invention.

According to a third aspect, the present invention provides an electronic device comprising: an input for receiving an AC current from a resonant circuit; An output for supplying DC current to the load; And a control circuit electrically coupling the input and the output, comprising: a diode bridge, shunt switches, and control means for selectively operating the switches; It can be said that a wide range of inductive power transfer (IPT) pickup controller including the control circuit for shunting two diodes.

Advantageously, said control means is adapted to selectively shunt said first and second diodes using said shunt switches such that respective predetermined ratios of positive and negative periods of said AC current are caused by said diode bridge. Rectified and supplied to the output, the remaining proportions of each of the positive and negative periods of the AC current are recycled to the resonant circuit.

Advantageously, said shunt switches comprise two switches, each of said two switches being provided in parallel with respective said first and second diodes, said first and second diodes being a common anode. has an anode.

Alternatively, the shunt switches may comprise two switches with a common cathode, each provided in parallel with respective first and second diodes.

Advantageously, said switches comprise MOSFET transistors and said first and second diodes comprise body diodes of said MOSFET transistors.

Advantageously, said control means further comprises sensing means for forming a feedback loop for sensing said output and for adjusting said predetermined ratios to obtain a desired output.

Advantageously, said control means further comprises a zero-crossing detector for synchronizing the shunt of said first and second diodes with respect to said sign change point of said AC current.

According to a fourth aspect, the invention is adapted to perform the method according to the first aspect of the invention, and / or is broadly applicable to an IPT pickup comprising an IPT pickup controller according to the second or third aspects of the invention. It can be said that it is configured.

Preferably, the resonant circuit comprises a series parallel tuning LCL (inductor-capacitor-inductor) resonant circuit.

According to a fifth aspect, the invention is broadly directed to an IPT system comprising at least one pickup controller according to the second or third aspects of the invention, and / or at least one IPT pickup according to the fourth aspect of the invention. It can be said that it is configured.

Other aspects of the invention, which should be considered all new aspects, will become apparent from the following description.

A number of embodiments of the invention will be described below by way of example with reference to the drawings.
1 is a circuit diagram of a serial parallel tuning LCL pickup according to the prior art.
2 is a circuit diagram of a serial parallel tuned LCL pickup according to the present invention.
FIG. 3 shows simulated waveforms of an example of a circuit as shown overall in FIG. 2 when operating in a first mode (which is mode I).
4 shows simulated waveforms of the same exemplary circuit when operating in the second mode (mode II).
FIG. 5 is a graph showing the output current versus switch conduction interval normalized for various VDC / Voc ratios for the same example circuit when operating in mode I.
6 is a graph showing the output current versus switch conduction interval normalized for various VDC / Voc ratios for the same example circuit when operating in mode II.
FIG. 7 is a graph showing reflected reactive impedance versus switch conduction spacing normalized for various VDC / Voc ratios for the same exemplary circuit when operating in Mode I. FIG.
8 is a graph showing the reflected reactive impedance versus switch conduction interval normalized for various VDC / Voc ratios for the same example circuit when operating in mode II.
9 shows actual waveforms of an exemplary pickup circuit according to the invention using the circuit of FIG. 2 and operating under mode I at a half rated load.
FIG. 10 shows actual waveforms of an exemplary pickup circuit according to the present invention using the circuit of FIG. 2 and operating in mode I under various load conditions (1/3, 2/3 and rated load).
FIG. 11 shows efficiency measurements of the pickup circuit according to the invention using the circuit of FIG. 2 and operating in mode I over a load range.

The same reference numbers in the description will be used to refer to the same features in different embodiments.

The present invention provides a control method and / or circuit for a series parallel tuned LCL pickup that achieves both rectification and power regulation. The present invention is generally referred to herein as "circulating current control." It operates in a manner similar to a conventional SCR controlled rectifier in which the switches are controlled to switch synchronously with the IPT track frequency. Duty cycle is controlled to ensure smooth average output power is achieved, providing smooth power transitions between fully on and fully off, or fast switching (i.e., switching frequency is similar to IPT track frequency). Or synchronized with this frequency).

Referring first to the prior art pickup shown in FIG. 1, the characteristic impedance X is given by:

Here, Cseries is used to increase output current performance. The values of L3 and C3 are chosen to operate the rectifier under continuous conduction for maximum output power, and are also designed to accommodate the additional inductance introduced by the nonlinear effect of the rectifier, minimizing the current at L2. The low speed switching controller for the LCL network operates in a similar way to the parallel tuning circuit except that in other respects the resonance collapses when the switch is closed in the parallel LC circuit, where the total resonant current in the LCL topology Still circulates through C2, L3, C3 and rectifier. The real part of the reflected impedance Zr of the LCL network at L1 is represented by:

VDC is the regulated DC output voltage of the circuit as shown in FIG. 2 and Voc is the open circuit voltage of the pickup coil.

As shown in equation (2), the reflected impedance corresponding to the power drawn by the pickup to the original primary track is controlled directly by the switch duty cycle (D). When the value of D changes from 1 (i.e., switch S in FIG. 1 is closed) to 0 (i.e., switch S is open) or from 0 to 1, it is drawn from the power source. The power is changed. In practice, however, the primary track current will also be excessively reduced and temporarily affect the power transfer for other pickups on the same track.

The proposed circulating current control circuit preferably comprises four diodes D1, D2, D3, and D4 in the diode bridge rectifier configuration, as shown by way of example in FIG. 2, and the switches S1 and S2) shunts the first and second diodes D1 and D2 respectively to close the switch S1 or S2 so that the current is recycled in the AC resonant circuit during the positive or negative period of IL3 respectively. In practice, however, the shunted diodes of the diode bridge may comprise body diodes of MOSFET transistors forming the switches S1 and S2.

The control circuit couples the AC current input to the DC output. In FIG. 2, the DC output is shown connected to the load RDC. The control circuit may include a reservoir or smoothing capacitor (CDC) across the output / load, as shown.

Switches S1 and S2 are used to clamp a portion of the resonant current at L3 IL3. Vg1 and Vg2 are pulse-width modulated (PWM) gate signals that drive S1 and S2, and are synchronized with IL3 as described in more detail below, for example, using a sign change point detector. . Terms such as "synchronized", "synchrony", etc., as used herein, are intended to refer to the precise control of the time at which switching occurs for an AC current input. The phase angle between the AC input and the switching does not necessarily coincide with the sign conversion point of the AC current input, for example, to adjust or otherwise control the output of the IPT pickup controller so that the switching occurs at exactly the same time per cycle. To control the code conversion point and change it if necessary.

To those skilled in the art, it is apparent that similar control outputs can be achieved when the two control switches are moved to shunt the top of the two diodes rather than the bottom of the two diodes of the rectifier. In this case, the switches S3 and S4 can be operated to shunt D3 and D4 and can also be operated in two possible control modes (as discussed herein) to achieve a similar result. have. In this configuration, the gate drive signals discussed herein for S1 will be used to drive S4, while the gate drive for S2 will be used to drive S3. Other such variations or modifications of the circuit are possible without departing from the scope of the invention.

The pickup controller circuit of the present invention can be operated in two ways. The first mode of operation allows D3 or D4 to be inverted at the start of the positive or negative period of IL3, respectively, then turn on S1 or S2 to clamp a portion of IL3 to regulate the output power. It is. As previously mentioned in this document, this mode of operation is referred to as mode I.

The second mode of operation is to keep S1 or S2 conducting at the start of the positive or negative period of IL3, and then turn off the switch to enable a portion of IL3 to be transferred to the load. As previously mentioned in this document, this mode of operation is referred to as mode II.

The switches S1 and S2 may be controlled using any suitable control means, such as, for example, a microcontroller and / or a logic circuit. The control means may comprise sensing means (which sense pick-up output current, voltage and / or power) and a feedback loop which enables control and / or adjustment of the pickup circuit output. Accordingly, various different control means can be used without departing from the scope of the present invention. Implementation of suitable control means is considered to be within the capabilities of one of ordinary skill in the art.

The operation of mode I is illustrated in the waveforms of FIG. 3.

The rising edge of the gate signals and thus the duty cycles of Vg1 and Vg2 are the phase delays [theta] 1 referenced to the sign transition points from positive to positive and from positive to negative respectively of IL3 as shown in FIG. (Referred to as diode conduction spacing).

At t0, current IL3 changed to membrane plus. When the first switch S1 is in the default off state, the diode D3 starts to conduct. The current IL3 is then transmitted to the load RDC through the body diode D2 of D3 and S2 at a predetermined rate of the positive period of the current IL3. The instantaneous output voltage of the LCL network is equal to + VDC.

At t1 when the diode conduction interval θ1 is reached, S1 is turned on and IL3 is cycled through the body diode D2 of S1 and S2, so that power is loaded at the remainder of the positive period of the current IL3 at the load RDC. Stop transmission to Instead, the current is recycled to the resonant circuit.

At t2 = T / 2, IL3 is negatively changed such that D4 is conducted at a predetermined rate of the negative period of IL3 and the circuit comprises the first diode D1, the body diode of S1. While the S1 body diode D1 is conducting, S1 may be turned off with zero current. The instantaneous value of VLCl is -VDC. If the phase delay (diode conduction spacing) [theta] 1 remains constant, the power transferred to the load RDC is the same in the second (negative) half cycle.

At t3, gate signal Vg2 keeps IL3 circulating through the body diode D1 of S2 and S1 at the remainder of the negative period of IL3, turning on S2 to recycle the current in the resonant circuit. Since IL3 circulates through the body diode of S1, the gate signal Vg1 can turn S1 off at any time between T / 2 and T.

Thus, when the switches S1 and S2 are controlled so that they are synchronized with IL3, the output current ID3 + ID4 is rectified and chopped (almost) sine wave. By controlling the diode conduction spacing [theta] 1 or equivalently the switch conduction spacing [theta] 2 (where [theta] 2 = T / 2-[theta] 1), the average output current is controlled directly and smoothly. θ1 may vary from 0 to π.

Mode II operation is illustrated in FIG. 4. It operates in a very similar way to mode I, but in a different switching sequence. The falling edges of the gate signals and thus the duty cycle of Vg1 and Vg2 are controlled by the switch conduction interval θ2 referred to IL3 as shown in FIG.

Before the current IL3 is changed from t0 to positive, the body diode D1 of the switch S1 is already turned on with IL3 flowing in the negative direction. Thus, turning on S1 during the negative period of IL3 will result in zero current / zero voltage switching.

At t0, IL3 changes to plus. When S1 is turned on, IL3 is recycled to the resonant circuit through S1 and the second diode D2, ie the body diode of S2. No power is sent to the load RDC at this rate of IL3's positive period (equivalent to the “rest ratio” of the positive period in Mode I operation).

At t1, when the switch conduction interval θ2 is reached, S1 is turned off and IL3 is turned on via D3 and body diode D2 of switch S2 to transfer power to the load at a predetermined rate of the positive period of IL3. Circulate During this ratio, the instantaneous LCL output voltage (VLCL) is + VDC. At any time between t0 and T / 2, Vg2 may turn on S2 with zero current / zero voltage switching, such as S1.

At t2 = T / 2, IL3 is negatively converted such that D3 is smoothly turned off and IL3 is recycled to the resonant circuit through the body diodes of S2 and S1.

At t3, gate signal Vg2 turns S2 off to enable IL3 to transfer power to D3 through the load at a predetermined rate of the negative period of IL3. The instantaneous value of the LCL output voltage (VLCL) is -VDC.

When the switch conduction spacing [theta] 2 and the diode conduction spacing [theta] 1 are kept constant, the power transmitted to the output in each half cycle is the same.

By synchronously controlling the switch conduction interval θ2 of both switches S1 and S2 to IL3, the output power is controlled directly and smoothly. This provides the ability to adjust the output power to a variable mutual coupling as compared to conventional low speed switching control topologies. In addition, the present invention ramps up and ramps down the duty cycle from zero power to full power to provide an alternative between fully on and fully off states of LCL pickup in slow switching applications. By enabling a smooth transition, track current transient disturbances are minimized.

Derivation of the theoretical representation for describing the DC output current for either the diode conduction spacing θ1 or the switch conduction spacing θ2 is impractical. Instead, numerical solutions are presented below. The cyclic current controller for both proposed operating modes is simulated with various ratios of VDC / Voc. The normalized output current for different VDC / Voc ratios is shown in FIG. 5 for mode I operation. Where Idc_max is the ideal maximum output current of the LCL pickup, given by:

The SPICE simulation results shown in FIG. 5 demonstrate that the relationship between the output current and the switch conduction spacing θ2 is not affected by VDC / Voc. This is due to the output current source characteristics of the LCL network. The ideal output DC current of the LCL network is a rectified sine wave with zero switch conduction spacing. When harmonics are introduced into the output current by the rectifier, this causes the output current to be slightly distorted from the ideal sine wave. Thus, at zero switch conduction interval, the normalized maximum output current is about 0.95 instead of 1. In the case where the switch conduction interval θ2 is controlled from 0 ° to 180 °, the output power can be accurately controlled and adjusted according to the relationship shown in FIG.

The simulation results shown in FIG. 5 (and the following figures) are for a specific example of a circuit according to the invention, as shown entirely in FIG. 2. For different LCL designs (ie different inductance and capacitance values), the profile of the output current and the reflection impedance will be different.

Simulation results of the output current normalized for various VDC / Voc ratios in mode II operation are shown in FIG. 6. Similar to mode I, the normalized DC output current for the switch conduction interval θ2 is the same for the various VDC / Voc ratios. However, the relationship between the output DC current and the switch conduction interval θ2 is completely different. Between 0 ° and 20 °, the output DC current increases with increasing switch conduction interval instead of decreasing as in mode I. Between 20 ° and 180 °, the DC current drops with increasing switch conduction spacing. Compared to mode I, the decay of the DC current is very slow for mode II operation. This is thought to be caused by additional current harmonics introduced by the switching operation. In the case of mode I operation, the harmonics introduced are circulated through the switches and L3 instead of circulating to the load. Therefore, in the case of current harmonics introduced into IL3 between the switch conduction intervals of 0 ° to 20 °, the final output power is greater than when the switches are completely off, and the different total output current action is between these two operations. Is observed.

The output power is controlled when the pickup switch conduction interval θ2 varies from 0 ° to 180 °, but the phase of the LCL AC basic output voltage is also converted for IL3. This introduces an additional Var load into the LCL network for both modes of operation. This Var load causes the power supply to slightly mistune, reflecting back onto the primary track. Simulation results of normalized reactive reactive impedance for various ratios of VDC / Voc are shown in FIGS. 7 and 8 for Mode I and Mode II operation, respectively.

In mode I operation (as shown in FIG. 7), the reflected impedance is swinged between an inductive load and a capacitive load for different switch conduction intervals. When the switch conduction spacing [theta] 1 is maintained between 0 [deg.] And 135 [deg.], The reflected load seen by the primary track which slightly increases the track inductance is inductive. This occurs because the phase of the VLCL leads to IL3. In the case of an increase in phase difference between VLCL and IL3, the reflected inductive load continues to increase. This increase in the reflected inductive load is gradually decelerated until the switch conduction interval θ2 reaches about 90 °, which begins to decrease. This is because the magnitude of the VLCL continues to decrease with increasing switch conduction interval θ2. Therefore, the increase in phase difference between VLCL and IL3 is less dominant. When the switch conduction spacing [theta] 2 is changed between 135 [deg.] And 180 [deg.], The reflected impedance for the primary is capacitive, which slightly reduces the track inductance. This is because the combined impedance of L3 and C3 is usually less than X to accommodate the inductance introduced by the rectifier. The amount of reflected impedance back to the original track is proportional to the VDC / Voc ratio.

Unlike mode I operation, the reflection impedance during mode II operation is fully capacitive, as shown in FIG. This is because the phase between VLCL and IL3 is in the opposite direction to Mode I (ie, where VLCL lags behind IL3 in Mode II). The maximum reflected reactive impedance occurs at the same conduction spacing of 90 °, which is proportional to the VDC / Voc ratio under mode 1 operation.

Exemplary embodiments of the invention are described below by way of example. The 2.5 kW 50V implementation of the proposed cyclic current duty cycle controlled pickup was built and tested using a commercially available Wampfler ™ 10 kW IPT power supply, which also supports LCL resonant networks for AGV (automated guided vehicle) applications. use. However, the pickup of the present invention may be used with any suitable power source, as will be appreciated by those skilled in the art.

Pickup parameters and track inductance of this example are listed in Table 1 below.

Oscilloscope capture of the pickup operating at half the rated power is shown in FIG. 9 operating in mode I. The top waveform is the current at L3 (IL3), the second waveform is the LCL AC output voltage VLCL, while the third waveform is the total output current (ID3 + ID4) of D3 and D4. The last (bottom) waveform is the switch gate drive signal Vg1. This capture indicates that the output voltage VLCL of the AC tuning network is successfully controlled by controlling the diode conduction spacing θ1 for IL3.

10 shows an oscilloscope capture of a pickup operating in mode I at different load conditions, without a switch gate drive waveform. FIG. 10A shows the operation at 1/3 rated load, FIG. 10B shows the operation at 2/3 rated load, and FIG. 10C shows the operation at rated load.

Pickup efficiency measurements under various load conditions are shown in FIG. 11. As can be seen from FIG. 11, the exemplary pickup achieves 88% efficiency at full load and is higher than 85% at half load. The controller operates at 50V and 50A, where high efficiency is difficult to achieve.

As discussed above, the cyclic current duty cycle control method of the present invention reflects variable reactive impedance in accordance with the controlled switch conduction interval. In the case of the system parameters shown in Table 1, the maximum reflected reactive impedance of the prototype system can be calculated using FIGS. 7 and 8.

In the case of Mode I operation, the maximum reflection inductive load occurs at a switch conduction interval of 80 °, as shown in FIG. The maximum reflective capacitive load occurs at 180 ° corresponding to the state where the pickup is completely off. The calculated maximum reflection inductive impedance is 0.0415Ω, which corresponds to increasing the primary track inductance by 0.33 μH. Since the Wampfler 10kW primary power track is tuned to 26μH with a tolerance of +/- 2μH, it will require 6 pickup controllers operating simultaneously at 80 degree switch conduction intervals to accumulate up to 2μH. This example system is not designed to deliver more than four pickups at any time to prevent power overloads, so the reflective inductive load will not be a problem in this design. On the other hand, the maximum reflective capacitive impedance is -0.0726Ω, which corresponds to reducing the primary track inductance by 0.577 μH. It will take up to four controllers that are completely off to exceed the -2μH threshold.

In the case of mode II operation, the reflective reactive impedance is fully capacitive and the maximum reflective impedance occurs at 80 ° switch conduction intervals as discussed above. Using Table 1 and FIG. 8, the maximum reflected reactance is -0.151Ω, corresponding to reducing the primary track inductance by only 1.202 μH. If more than one pickup on the track is switched simultaneously, the detuning effect on the power supply will exceed the 2 μH threshold. Therefore, the cyclic current duty cycle control under such a situation can be used as a transition scheme between the pickup controller which is completely off and on in the low speed switching control method. In the case of a sequential switching (ie interleaving switching) control method, pickups within 2 may be switched on the same track at the same time when operating in mode II to avoid reflective reactance overloads at the power source. However, a power supply employing an LCL resonant network topology has a better tolerance because its track inductance is less than its design value, while only slightly negotiating the maximum power rating of the power supply. Therefore, even if the additional Var load introduced by the proposed cyclic current duty cycle controller slightly detunes the primary power supply, in practice this VAR load can be easily handled by normal system parameter tolerances.

As mentioned above, the method of the present invention may comprise any form of computing means or digital or mixed signal computing device or processor, for example adapted to provide suitable gate voltages to switches S1 and S2. Typically implemented by control means, such as a microcontroller. When programmed to perform certain functions in accordance with instructions from program software implementing the method of the present invention, the computing device is effectively a special purpose computing device specific to the method of the present invention. The techniques required for this are well known to those skilled in the art of embedded systems.

Computer programs that implement the methods of the present invention may be distributed to users with distribution media, such as floppy disks, CD-ROMs, or USB flash memory. From there, the programs can be copied to a hard disk, embedded solid-state memory, or similar intermediate storage medium. When the programs are executed, the programs will be loaded into the execution memory of the computing means from either their distribution medium or their intermediate storage medium to configure the computing means to operate according to the method of the present invention. All such operations are well known to those skilled in the art of computer systems.

The term "computer-readable medium" refers to a distribution medium, an intermediate storage medium, an executable memory of a computer, and any other that can be stored for later reading by a computing device implementing the method of the present invention. Media or devices.

Alternatively, the method of the present invention may be performed entirely by a plurality of discrete electronic components and / or application specific integrated circuits (ASICs), for example in hardware.

Therefore, the present invention, and in particular the control means, may comprise a computer program adapted to carry out the method of the present invention, a computer readable medium storing such computer program, and / or a hardware system adapted to carry out the above-described method of the present invention. It can be configured.

From the foregoing, it will be appreciated that a pickup control method and pickup controller are provided that allow adjustment of output power in a low speed switching serial parallel tuned LCL pickup topology. This adjustment enables ramping up / down between any or all of the compensation for changes in mutual coupling between the pickup and the primary track, and pickup output levels to minimize track current transient disturbances.

Unless the situation clearly requires otherwise in the description, the words "comprise", "comprising", etc., are used in a comprehensive sense, ie, "comprising," as opposed to a monopolistic or exhaustive meaning. It should be interpreted in the sense of including, but not limited to.

Although the invention has been described with reference to examples and possible embodiments thereof, it should be understood that modifications or improvements can be made thereto without departing from the scope of the invention. The invention is broadly comprised of parts, elements and features referred to or indicated in the specification of the present application, individually or collectively, any two or more of said parts, elements or features Or it can be said that it consists of all combinations. Moreover, although reference has been made to certain components or integers of the present invention having known equivalents, such equivalents are then incorporated herein as if individually presented.

The discussion of the prior art throughout this specification should not be considered as acknowledging that such prior art is widely known or forms part of the general knowledge common in the art.

Claims (18)

A method of controlling inductive power transfer (IPT) pick-up including an AC input from a resonant circuit, wherein the AC input rectifies AC current from the AC input and directs DC current to DC. The method, electrically coupled to a diode bridge adapted to supply to the output,
Selectively shunting a first diode of the diode bridge to cause the AC current to be recycled to the resonant circuit during a positive period of the AC current; And
Selectively shunting a second diode of the diode bridge to cause the AC current to be recycled to the resonant circuit during a negative period of the AC current;
The shunt of the first and second diodes is synchronized with the AC current whereby the predetermined ratio of the positive and negative periods of the AC current is rectified to supply the DC current to the DC output, And the remaining ratio of the positive and negative periods of AC current is recycled to the resonant circuit. The method according to claim 1,
The predetermined ratio occurs at the start of each of the positive and negative periods of the AC current, and the first or second diode conducts the AC current after each zero-crossing of the AC current, respectively. and the remaining ratio of the positive or negative period is recycled by shunting each of the first or second diodes at an appropriate time. The method according to claim 1,
The predetermined ratio occurs towards the ends of each of the positive and negative periods of the AC current, and the first or second diodes respectively at each sign change point of the AC current to initially recycle the AC current. And wherein each said first or second diode is not shunted to conduct said AC current at said predetermined rate of said positive or negative period. The method according to any one of claims 1 to 3,
The predetermined ratio of the positive and negative periods is proportional to a desired DC output, and the method further comprises sensing the DC output and adjusting the predetermined ratio appropriately to obtain the desired DC output. , Control method of inductive power transfer pickup. The method according to any one of claims 1 to 4,
And the method further comprises gradually increasing the predetermined rate to a required rate in accordance with switching on of the pickup. The method according to any one of claims 1 to 5,
The method further comprising gradually decreasing the predetermined ratio to zero upon switching off of the pickup. The method according to any one of claims 1 to 6,
And the shunt is selectively controlled by selectively closing first and second switches provided in parallel with the respective first and second diodes. The method of claim 7,
And the first and second switches are opened when the first or second diodes are being conducted, respectively. An inductive power transfer (IPT) pickup controller adapted to carry out the method according to any one of claims 1 to 8. Induction Power Transfer (IPT) pickup controller,
An input for receiving AC current from the resonant circuit;
An output for supplying DC current to the load; And
A control circuit electrically coupling the input and the output, comprising: a diode bridge, shunt switches, and control means for selectively operating the switches, the first and second of the diode bridge synchronously with the AC current. An inductive power transfer pick-up controller comprising the control circuit for shunting diodes. The method of claim 10,
The control means is adapted to selectively shunt the first and second diodes using the shunt switches such that respective predetermined ratios of the positive and negative periods of the AC current are rectified by the diode bridge and the output And the remaining proportions of each of the positive and negative periods of the AC current are recycled to the resonant circuit. 12. The method according to claim 10 or 11,
The shunt switches comprise two switches, the switches being provided in parallel with the respective first and second diodes, the first and second diodes having a common anode. Pickup controller. The method according to any one of claims 10 to 12,
The switches include MOSFET transistors, and the first and second diodes comprise body diodes of the MOSFET transistors. The method according to any one of claims 10 to 13,
The control means further comprises sensing means for forming a feedback loop for sensing the output and for enabling adjustment of the predetermined ratios to obtain a desired output. The method according to any one of claims 10 to 14,
And the control means further comprises a sign change point detector for synchronizing the shunt of the first and second diodes with respect to the sign change point of the AC current. An inductive power transfer pickup, adapted to perform the method according to any one of claims 1 to 8 and / or comprising an inductive power transfer pickup controller according to any one of claims 9 to 15. 18. The method of claim 16,
The resonant circuit comprises a series parallel tune LCL (inductor-capacitor-inductor) resonant circuit. Inductive power transfer system comprising at least one pickup controller according to any one of claims 9 to 15 and / or at least one inductive power transfer pickup according to claim 16 or 17.

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